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Deep ocean carbonate ion increase during mid Miocene CO2 decline

Deep ocean carbonate ion increase during mid Miocene CO2 decline | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

Characterised by long term cooling and abrupt ice sheet expansion on Antarctica ~14 Ma ago, the mid Miocene marked the beginning of the modern ice-house world, yet there is still little consensus on its causes, in part because carbon cycle dynamics are not well constrained. The authors used benthic foraminiferal B/Ca ratios to reconstruct relative changes in [CO32−] from the South Atlantic, East Pacific, and Southern Oceans. Our results suggest an increase of perhaps ~40 μmol/kg may have occurred between ~15 and 14 Ma in intermediate to deep waters in each basin.

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Imaging nanopores

Imaging nanopores | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

Microimaging techniques, such as interference and infrared microscopy, can be used as a tool to directly monitor guest profiles within nanoporous materials. Observation of the variation in these profiles leads to unprecedented insight into transport phenomena, including intracrystalline diffusion and surface permeation.

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EAG at EGU2014 « European Association of Geochemistry

The European Association of Geochemistry, EAG, aims to promote geochemical research in Europe.
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Why Mineral Interfaces Matter

Why Mineral Interfaces Matter | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

Throughout Earth, rocks respond to changing physical and chemical conditions by converting one rock type to another. These conversions have conventionally been described in terms of solid-state mechanisms, in which new minerals nucleate and grow through exchange of elements by diffusion. The slow rates of solid-state diffusion suggested geological time scales for these processes. However, rocks in Earth's crust are not dry!

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Uranium-bearing phosphatized limestones of NW Greece

Uranium-bearing phosphatized limestones of NW Greece | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

Sedimentary Mesozoic rocks from NW Greece (Epirus region), and particularly laminated phosphatized limestones, bedded chert-rich limestones and brecciated phosphatized limestones, were examined for their actinide content. Gamma-ray measurements using a HPGe detector showed that the above geological materials exhibit high radioactivity, mainly attributed to the 238U-series. The 238U content (up to 7700 Bq/Kg) was determined by the 1001 keV photopeak of 234mPa, the 238U daughter. Bulk geochemical analyses using ICP-OES/MS showed variable U concentrations with a notable value of 648 ppm in the case of dark organic-rich material hosted into the brecciated phosphatized limestones. Relatively high concentrations of Cd, probably related to apatite, were also revealed. On the other hand, the rock is geochemically depleted in LILE (e.g. Cs, Rb, K), as well as in As, Sb and Se in contrast to “average phosphorite”. Powder-XRD combined with optical microscopy, SEM-EDS and FTIR confirmed abundant apatite, besides calcite, as well as organic compounds (organic matter/O.M.) which should be associated to the high U content. According to Th/Sc vs. Zr/Sc discrimination diagrams the organic-rich part of the U-bearing phosphatised limestones exhibits a mafic trend, in contrast to the rest of the studied rocks lying close to typical pelagic sediments. However, Eu/Eu* vs. Ce/Ce* diagrams, in combination with SEM-EDS, indicated that the organic-rich part is a typical sedimentary material whereas the organic-poor (and also U-poor) part of the rock is secondary calcite related to surface waters. As far as we know, the studied rocks from NW Greece are classified among the richest U-bearing phosphatized limestones and/or sedimentary phosphorites in the world.

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Nanoscale Reactivity of Biologically and Chemically Formed Green Rust Crystals

Nanoscale Reactivity of Biologically and Chemically Formed Green Rust Crystals | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

Using atomic and chemical force microscopy to probe the reactivity at the nanoscale of both types of nanoparticles, the authors were able to show that the primary reason for the low reactivity of b-GR is not the low surface/volume ratio but the passivation of the surface due to the presence of biological exopolymers (EPS).

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Mineral surfaces–RNA interactions

Mineral surfaces–RNA interactions | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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The authors present the results of large-scale molecular simulations, run over several tens of nanoseconds, of 25-mer sequences of single-stranded ribonucleic acid (RNA) in bulk water and at the surface of three hydrated positively charged MgAl layered double hydroxide (LDH) minerals. The three LDHs differ in surface charge density, through varying the number of isomorphic Al substitutions.

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Incorporation of Uranium into Hematite during Crystallization from Ferrihydrite

Incorporation of Uranium into Hematite during Crystallization from Ferrihydrite | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

TEM, and XAS techniques provided the first evidence that adsorbed U(VI) (≈3000 ppm) was incorporated into hematite during ferrihydrite aggregation and the early stages of crystallization, with continued uptake occurring during hematite ripening. EXAFS and XANES data indicated that the U(VI) was incorporated into a distorted, octahedrally coordinated site replacing Fe(III). Fitting of the EXAFS showed the uranyl bonds lengthened from 1.81 to 1.87 Å, in contrast to previous studies that have suggested that the uranyl bond is lost altogether upon incorporation into hematite.

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Association of Cardiopulmonary Health Effects with Source-Appointed Ambient Fine Particulate in Beijing, China

Association of Cardiopulmonary Health Effects with Source-Appointed Ambient Fine Particulate in Beijing, China | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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The authors examined the cardiopulmonary health effects of fine particles (PM2.5) from different pollution sources in Beijing, China, among a panel of 40 healthy university students.

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University of Saskatchewan to build new Synchrotron beamline to study the role of metals in the human body

University of Saskatchewan to build new Synchrotron beamline to study the role of metals in the human body | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
The provincial government has given the University of Saskatchewan 2.1-million dollars for nine research projects.
Ath Godelitsas's insight:

More than half of the budget will be used for the new BioXAS beamline project, Canada Research Chair and lead researcher Graham George said. The beamline will be useful in researching Alzheimer's disease and multiple sclerosis. "Both of these diseases involve metals". "We're not really sure if they're part of the problem or they're part of the cause of the problem, but we know they're involved and we want to understand this."

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Dust in the wind drove iron fertilization during ice age

Dust in the wind drove iron fertilization during ice age | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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Martínez-García et al. (http://www.sciencemag.org/content/343/6177/1347.abstract) investigated the isotopic composition of foraminifera-bound nitrogen in samples from an Ocean Drilling Project sediment core and found millennial-scale changes in nitrate consumption correlated with fluxes in the iron burial and productivity proxies over the past 160,000 years. Hence, in the Southern Ocean the biological pump was strengthened when dust fluxes were high, which explains a significant part of the difference in atmospheric CO2 concentrations observed to occur across glacial cycles.
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Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing

Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Low levels of iron limit primary productivity across much of the Southern Ocean. Measurements of dissolved iron levels combined with hydrographic data suggest that much of the iron in the surface waters of the Southern Ocean is supplied by deep mixing during winter.
Ath Godelitsas's insight:

The authors have analysed data on dissolved iron concentrations in the top 1,000 m of the Southern Ocean, taken from all known and available cruises to date, together with hydrographic data to determine the relative importance of deep winter mixing and diapycnal diffusion to dissolved iron fluxes at the basin scale. They concluded that winter mixing and surface-water iron recycling are important drivers of temporal variations in Southern Ocean primary production.

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Data-mining for Crystal 'Gold' at SLAC's X-ray Laser | SLAC National Accelerator Laboratory

Data-mining for Crystal 'Gold' at SLAC's X-ray Laser | SLAC National Accelerator Laboratory | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

A new tool for analyzing mountains of data from SLAC’s Linac Coherent Lightsource (LCLS) X-ray laser can produce high-quality images of important proteins using fewer samples. Scientists hope to use it to  reveal the structures and functions of proteins that have proven elusive, as well as mine data from past experiments for new information.

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Calcitic marine shell’s defensive armor revealed

Calcitic marine shell’s defensive armor revealed | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
To ensure survival, the exoskeletons of biological species are required to minimize the spatial extent of damage following attack or multi-hit events. Now, nanoindentation experiments on a transparent bivalve shell, which is made up of layered, diamond-shaped calcite crystals, show an increased energy dissipation density compared with single-crystal calcite, resulting in penetration resistance and deformation localization. The detailed mechanisms of this enhanced energy dissipation are revealed and include nanoscale deformation twinning around the penetration zone.
Ath Godelitsas's insight:

Researchers at MIT have analyzed shells to determine exactly why they are so resistant to penetration and damage, even though they are 99 percent calcite, a weak, brittle mineral. The shells’ unique properties emerge from a specialized nanostructure that allows optical clarity, as well as efficient energy dissipation and the ability to localize deformation, the researchers found. The results are published this week in the journal Nature Materials, in a paper co-authored by MIT graduate student Ling Li and professor Christine Ortiz (see also: https://newsoffice.mit.edu/2014/tough-nails-yet-clear-enough-read-through).

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Potential influence of sulphur bacteria on Palaeoproterozoic phosphogenesis

Potential influence of sulphur bacteria on Palaeoproterozoic phosphogenesis | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it

HAADF detector image of apatite (bright) cylinders in the matrix of carbonaceous matter

Ath Godelitsas's insight:

The authors have used microfabric, trace element and carbon isotope analyses to assess the environmental setting and redox conditions of the 2-billion-year-old P-rich deposits of the vent- or seep-influenced Zaonega Formation, northwest Russia. they identified phosphatized microorganism fossils that resemble modern methanotrophic archaea and sulphur-oxidizing bacteria, analogous to organisms found in modern seep settings and upwelling zones with a sharp redoxcline.

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Evidence for oxygenic photosynthesis half a billion years before the Great Oxidation Event

Evidence for oxygenic photosynthesis half a billion years before the Great Oxidation Event | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

The evolution of oxygenic photosynthesis should have occurred some time before the oxidation of Earth/'s atmosphere 2.5 billion years ago. The molybdenum isotopic signature of shallow marine rocks that formed at least 2.95 billion years ago is consistent with deposition in waters that were receiving oxygen from photosynthesis at least half a billion years before the oxidation of the atmosphere.

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Strong, tough and stiff bioinspired ceramics from brittle constituents

Strong, tough and stiff bioinspired ceramics from brittle constituents | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
The toughness of ceramic materials can be improved by introducing a polymeric or metallic ductile phase, yet most often this is at the expense of strength, stiffness and high-temperature stability. Now, a simple processing route based on widespread ceramic processing techniques is shown to produce bulk ceramics that mimic the structure of natural nacre and have a unique combination of high strength, toughness and stiffness, even at high temperatures.
Ath Godelitsas's insight:

Although natural materials that are both strong and tough rely on a combination of mechanisms operating at different length scales, the relevant structures have been extremely difficult to replicate. Here, the authors report a bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (22 MPa m1/2), and high stiffness (290 GPa). Because only mineral constituents are needed, these ceramics retain their mechanical properties at high temperatures (600 °C).

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Interaction of Hydrated Cations with Mica Surface

Interaction of Hydrated Cations with Mica Surface | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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Three brittle swelling micas, Mica-n (n = 4, 3 and 2), were selected in order to analyze the influence of the layer charge in the formation of inner-sphere complexes (ISC). The contribution of the ISC has been analyzed thorough the evolution of the 060 reflection and the changes in the short-range order of the tetrahedral cations will be followed 29Si and 27Al MAS NMR. The results showed that ISC was favored in X-Mica-4 and that provoked a high distortion angle between the Si–Al tetrahedra.

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Analysis of the Configurations of a Crystal Surface

Analysis of the Configurations of a Crystal Surface | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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As a case study, the authors studied the surface configurations of the {100}, {110}, and {112} forms of pyrope (Mg3Al2Si3O12). To identify the most stable surface termination, they have performed an accurate ab initio study of the surface structures and energies at 0 K of the pyrope {100} configurations, by using the hybrid Hartree–Fock/density functional B3LYP Hamiltonian and a localized all-electron Gaussian-type basis set.

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Ultrastructure and Crystallography of Nanoscale Calcite Building Blocks in Coccolith Spines

Ultrastructure and Crystallography of Nanoscale Calcite Building Blocks in Coccolith Spines | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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In this study, the structure of Rhabdosphaera clavigera is described in detail for the first time through a combination of electron microscopy techniques, including three-dimensional electron tomography.

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Vertical distributions of artificial radionuclides in sediment cores of lake Bosten in China

Vertical distributions of artificial radionuclides in sediment cores of lake Bosten in China | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
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In this paper the authors investigated the vertical distributions of 239+240Pu and 137Cs activities, 240Pu/239Pu atom ratios, and 239+240Pu/137Cs activity ratios in sediment cores collected from Lake Bosten, which is the lake closest to the Lop Nor Chinese Nuclear Weapon Test site in northwestern China.

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Sulphide oxidation and carbonate dissolution as a source of CO2 over geological timescales

Sulphide oxidation and carbonate dissolution as a source of CO2 over geological timescales | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Ath Godelitsas's insight:

During the Cenozoic era, spanning approximately the past 66 million years, the concurrent increases in the marine isotopic ratios of strontium, osmium and lithium suggest that extensive uplift of mountain ranges may have stimulated CO2 consumption by silicate weathering5, but reconstructions of sea-floor spreading6 do not indicate a corresponding increase in CO2 inputs from volcanic degassing. The resulting imbalance would have depleted the atmosphere of all CO2 within a few million years7. As a result, reconciling Cenozoic isotopic records with the need for mass balance in the long-term carbon cycle has been a major and unresolved challenge in geochemistry and Earth history. The authors here show that enhanced sulphide oxidation coupled to carbonate dissolution can provide a transient source of CO2 to Earth’s atmosphere that is relevant over geological timescales.

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Neither rare, nor earths

Neither rare, nor earths | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
You have probably never heard of most of the so-called rare earth elements yet they have insinuated themselves deep into the fabric of modern life.
Ath Godelitsas's insight:

In his laboratory in University College London, Prof Andrea Sella's face lights up when asked about rare earths. Clearly this family of elements is particularly close to the chemist's heart. The first thing you need to know is they are neither rare nor earths, he tells. They are known as "rare" because it is very unusual to find them in a pure form, but it turns out there are deposits of some of them all over the world - cerium, for example, is the 25th most common element on the planet. The term "earth" is simply an archaic term for something you can dissolve in acid.

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Earth's deep water reservoir

Earth's deep water reservoir | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it

A tiny sample of a mineral included in a diamond confirms predictions from high-pressure laboratory experiments that a water reservoir comparable in size to all the oceans combined is hidden deep in Earth's mantle.

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Pearson et al. (see: http://www.nature.com/nature/journal/v507/n7491/full/nature13080.html ) have discovered a microscopic sample of ringwoodite, a polymorph of the mineral olivine, in this diamond from Juína, Brazil. The diamond is 5 millimetres across in its longest dimension.

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The world's most important geochemistry conference is coming to Sacramento

The world's most important geochemistry conference is coming to Sacramento | Mineralogy, Geochemistry, Mineral Surfaces & Nanogeoscience | Scoop.it
Are you interested in energy, the environment, climate change, past, present, and future, the chemistry of the cosmos, emerging issues in energy resources, or g (http://t.co/uTwHGL5PKd)...
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